was explained to me last year by a BoatUS operator. If correct, BoatUS operators bill and get paid per incident from the insurance BoatUS provides and if the insurance doesn't cover than the boat owner makes up the difference. That's why it pays to have the unlimited coverage. SeaTow operators get the most all of the premium for the insurance they sell and then get paid nothing more to make a call unless the cost exceeds the insurance.
So SeaTow may take in $150,000 at the beginning of the season and have to budget themselves the entire season. BoatUS guys are always scrambling for a job and a tow. Rhetorically, who do you think is more likely going to come get you on a snotty night in a seaway?